Gamma-ray Astrophysics Mission, California Institute of Technology (GAMCIT)

Caltech's GAMCIT payload, the first space payload built by Caltech's chapter of the Students for the Exploration and Development of Space (SEDS) flew as a Get-Away Special payload on STS-77 in May 1996.

Read the GAMCIT Final Report and the cover letter.

The GAMCIT Safety Data Package (SDP) is also available (in MS Word format).

The mission operated for approximately seven days before battery power ran out and the experiment was shut down. Due to the film slipping off the sprockets during launch, the optical camera system failed to operate correctly, and no images were obtained. However, the gamma-ray detectors worked well, and we obtained nearly two gigabytes of data, including a gamma-ray burst!

The post-flight calibration data demonstrates that the gamma-ray detectors survived launch and landing without incident, and performed as expected. All of the electronic subsystems performed nominally throughout the mission, including the housekeeping sensors (temperature, pressure, battery voltage). The Global Positioning Satellite (GPS) receiver worked better than expected, providing the payload with accurate time and even acquired a few position fixes throughout the mission.

GAMCIT, originally designed by Astronaut John Grunsfeld , was designed to study an enigmatic source of cosmic radiation known as gamma ray bursts. While these intense bursts of high-energy radiation were first discovered in the late 1960s by satellites watching for clandestine nuclear tests, their precise nature and origin still remains an intriguing astrophysical mystery.

Many theories of the origin of gamma ray bursts also predict that a flash of visible light might accompany bursts. While many researchers have searched for these optical flashes after bursts are reported, GAMCIT was capable of simultaneously detecting gamma ray bursts and optical flashes using a 35-millimeter camera triggered a fraction of a second after each gamma ray burst.

GAMCIT also recorded the energy and arrival time of each incoming gamma ray photon. This will allow the GAMCIT team to perform microsecond timescale analysis of the structure of the bursts. GAMCIT also contains a space-qualified Global Positioning System (GPS) receiver -- the first ever to fly in a Get-Away Special payload. This GPS receiver will provided GAMCIT with accurate time and position data that can be used in post-flight data analysis.

While a Research Fellow at Caltech, Dr. Grunsfeld and SEDS members laid the initial groundwork for the experiment. After Dr. Grunsfeld joined the astronaut corps, the payload was designed and constructed by Caltech undergraduate students. The team leaders are Benjamin McCall (project manager), Albert Ratner (mechanical systems), and Michael Coward (electronics). Dr. Grunsfeld continues to advise the students involved in the project.

This project would not have been possible without generous help from our sponsors.

For more information, please contact:
Ben McCall, GAMCIT Project Manager
SEDS Officers

Other sites of interest:

  • G-200 -Another GAS payload which flew on STS-77
  • NASA GAS Homepage
    Caltech SEDS
    Mail Code 112-58, Caltech
    Pasadena, CA 91126
    (626) 395-2902
  • Ben McCall, February 12th, 1999